Do Yeast Cells Mutate Based upon Temperature?

[yournotpeter]

I like to use Kolsch yeast for a lot of different styles, and change my fermentation temperature to pull different characteristics. For example, I'm fermenting a Cream Ale right now at 68, but would like to reuse that yeast for an American Wheat and ferment that at 63. Can anyone tell me if the yeast mutated and physically changed when fermenting on the higher end of the strain at 68? In other words, am I getting a completely different yeast with the Wheat because it had fermented on the higher end? Thank you for any advice!

 

[mongoose33]

I like to use Kolsch yeast for a lot of different styles, and change my fermentation temperature to pull different characteristics. For example, I'm fermenting a Cream Ale right now at 68, but would like to reuse that yeast for an American Wheat and ferment that at 63. Can anyone tell me if the yeast mutated and physically changed when fermenting on the higher end of the strain at 68? In other words, am I getting a completely different yeast with the Wheat because it had fermented on the higher end? Thank you for any advice!

No, it didn't mutate.

However, yeast will express flavors differently depending on the temperature at which the yeast ferments the wort. In fact, that's one source of certain off-flavors; if you have fermentation at too high a temp, you may produce undesirable esters.

So, you may get a different result but not because the yeast mutated.

 

[yournotpeter]

yeast will express flavors differently depending on the temperature at which the yeast ferments the wort.

Yep, and I love the fact I can change the temps on that yeast to make it do some different things...but normally I use a fresh pitch and not reuse. I want to reuse and want to make sure the yeast I'm reusing (which fermented at 68) will be the same yeast when I then ferment it at 63. Thanks!

 

[isomerization]

I can almost guarantee you the yeast company you bought that yeast from grew the culture well above both of those temps.

Your risk for mutation increases with subsequent repitching (depending on how stressful the fermentation was).

 

[mongoose33]

I can almost guarantee you the yeast company you bought that yeast from grew the culture well above both of those temps.

Your risk for mutation increases with subsequent repitching (depending on how stressful the fermentation was).

That's really selection, not mutation.

 

[isomerization]

That's really selection, not mutation.

It can be both sure. Unless you’re suggesting that yeast have 100% DNA replication fidelity?

 

[Terpene]

It can be both sure. Unless you’re suggesting that yeast have 100% DNA replication fidelity?

Right, and plus there would be nothing to select for if no mutation(s) had already occurred and the population of cells was genetically identical.

 

[Terpene]

OP, if you're storing yeast and repitching it over time, storage method and temperature matter. Freezing temperatures will minimize genetic drift.

Also, if you're going to repitch more than a handful or so times, you probably don't want to do it serially (pitching the last yeast into the next beer). If you want to avoid genetic changes in the yeast over time, you're better off keeping and properly storing a small source supply and growing fresh starters from the source for each pitch or every several pitches.